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=============================================================================
FreeBSD-SA-02:11                                            Security Advisory
                                                                FreeBSD, Inc.

Topic:          ucd-snmp/net-snmp remotely exploitable vulnerabilities

Category:       ports
Module:         net-snmp
Announced:      2002-02-12
Credits:        OUSPG: Oulu University Secure Programming Group
                http://www.ee.oulu.fi/research/ouspg/
Affects:        Ports collection prior to the correction date
Corrected:      2002-01-21 16:54:50 UTC
FreeBSD only:   NO
CERT:           CA-2002-03

I.   Background

The Net-SNMP (previously known as UCD-SNMP) package is a set of Simple
Network Management Protocol tools, including an agent, library, and
applications for generating and handling requests and traps.

NOTE: The Net-SNMP port directory is ports/net/net-snmp, but the
package name is still ucd-snmp.

II.  Problem Description

The Net-SNMP port, versions prior to 4.2.3, contains several remotely
exploitable vulnerabilities.  The OUSPG has discovered vulnerabilities
in many SNMPv1 implementations through their `PROTOS - Security
Testing of Protocol Implementations' project.  The vulnerabilities are
numerous and affect SNMPv1 request and trap handling in both managers
and agents.  Please refer to the References section for complete
details.

The Net-SNMP port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains over 6000 third-party applications in a ready-to-install
format. The ports collection shipped with FreeBSD 4.5 does not
contains this problem.

FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.

III. Impact

Although no exploits are known to exist at this time, the
vulnerabilities may be exploited by a remote attacker in order to
cause the SNMP agent to execute arbitrary code with superuser
privileges.  Malicious agents may respond to requests with specially
constructed replies that cause arbitrary code to be executed by the
client.  Knowledge of the SNMP community name is unnecessary for such
exploits to be effective.


IV.  Workaround

1) Deinstall the ucd-snmp port/package if you have it installed.

V.   Solution

Do one of the following:

1) Upgrade your entire ports collection and rebuild the port.

2) Deinstall the old package and install a new package dated after the
correction date, obtained from the following directories:

[i386]
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/net/ucd-snmp-4.2.3.tgz

[alpha]
Packages are not automatically generated for the alpha architecture at
this time due to lack of build resources.

3) Download a new port skeleton for the net-snmp port from:

http://www.freebsd.org/ports/

and use it to rebuild the port.

4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/Latest/portcheckout.tgz

NOTE: Many other applications utilize the Net-SNMP libraries.  These
applications may also be vulnerable.  It is recommended that such
applications be rebuilt after upgrading Net-SNMP.  The following
command will display applications installed by the FreeBSD ports
collection that utilize Net-SNMP:

  pkg_info -R ucd-snmp-\*

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in the FreeBSD ports collection.

Path                                                             Revision
- -------------------------------------------------------------------------
ports/net/net-snmp/Makefile                                          1.59
ports/net/net-snmp/distinfo                                          1.15
ports/net/net-snmp/pkg-plist                                         1.18
ports/net/net-snmp/files/freebsd4.h                             (removed)
ports/net/net-snmp/files/patch-aclocal.m4                             1.1
- -------------------------------------------------------------------------

VII. References

<URL:http://www.cert.org/advisories/CA-2002-03.html>
<URL:http://www.ee.oulu.fi/research/ouspg/protos/>
<URL:http://www.kb.cert.org/vuls/id/107186>
<URL:http://www.kb.cert.org/vuls/id/854306>
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